The invention relates to a drive arrangement for roll bar of motor vehicles which are raised and locked in an extended position in response to a crash condition.
DE-OS 1,555,955, or U.S. Pat. No. 3,292,726, describes a roof reinforcing bar for motor vehicles which is held at each end by a telescopic support fixed to the motor vehicle chassis and comprises a piston-type telescopic extension which can be extended out of a cylinder and can be transferred by a compression spring out of a retracted position into an extended position. It is possible thereby to move the roof reinforcing bar out of the rest position into its supporting position.
Following the emission of a crash pulse, the extension movement of a roll bar, supporting the vehicle in the event of a roll-over on the ground, must take place rapidly and is achieved with a sufficiently high speed by prestressed compression spring acting on the extending piston.
However, many vehicle occupants absolutely refuse to drive a motor vehicle on which the roof has been removed unless the roll bar is in the erected supporting position. At the same time, it is perceived as unpleasant if the roll bar is erected abruptly by the compression spring. Another disadvantage is that it is not possible to interrupt the extension movement and to halt the roll bar before it has reached its end position. Thus a person sitting in the back risks being injured by the movement of the roll bar. It is equally impossible for the roll bar to be automatically retracted when required. Given a highly prestressed compression spring, it must be pressed back into its rest position with the exertion of a large force.
A motor drive roll bar is shown in U.S. Pat. No. 4,557,502.
It is the object of the present invention to make a roll bar which can be extended rapidly into its supporting position in a crash situation and usable even without a crash pulse.
This object is achieved by the following characterizing features.
The driven piston can be extended and also retracted at a moderate pace and by virtue of this the movement of the roll bar also proceeds slowly and in controllable manner. Should the roll bar endanger an occupant during its controlled movement, the roll bar can be halted and its direction of movement reversed.
If a crash pulse is triggered during the controlled movement, the action of the drive on the piston is cancelled, thereby causing the roll bar, driven by the ejection spring, to extend rapidly into its supporting position.
It is possible to lock the support piston in any position against being driven. Thus the roll bar supports the vehicle in the event of a roll-over even when, in an unfavorable case, it has not yet quite reached its fully extended supporting position. If an additional piston-cylinder unit is chosen as drive for the support piston, then it is advantageous to connect these pistons releasably via a crash coupling. Thus, following a crash pulse, the drive can be disconnected from the support piston, which then moves out unretarded and accelerated by the ejection spring into its supporting position. The same result can be achieved if the cylinders of the two piston-cylinder units are locked releasably to one another. In this arrangement, following a crash pulse, the drive piston together with its cylinder is carried along by the spring-loaded support piston. Since the cylinder remains in alignment by virtue of a guide sleeve, it can be driven back along the guide sleeve into the locking arrangement in order to re-establish the connection between the two cylinders.
In one possible embodiment of a crash coupling which, after being complemented by loading the locking pin with a prestressed stressing spring, it becomes a prestressable crash coupling which does not require an external control signal at the crash coupling to re-establish the connection between the two pistons.
Further appropriate embodiment of a drive and possible embodiments of a locking arrangement for the support and the drive cylinder are also described.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.